The region, home to 1.9 billion people, appears to have been less badly affected than other parts of the world
Pakistan suspended on Saturday all international flights for two weeks to limit the spread of coronavirus, as governments across densely populated South Asia ramped up their efforts to contain the virus.
Pakistani officials also asked people to self-quarantine for at least another 45 days as the country reported its third coronavirus death, with confirmed cases rising to 534.
"(The) government of Pakistan has decided to suspend operation of all international passenger, chartered and private flights to Pakistan, effective from March. 21 till April 4, the civil aviation ministry said in a statement.
Authorities in Bangladesh tightened border controls, while Sri Lankan police arrested more than two dozen people for violating a nationwide curfew.
The region, home to 1.9 billion people, appears to have been less badly affected than other parts of the world, but the rate of new infections in Pakistan, India, Nepal, Bhutan, Sri Lanka has accelerated.
As a whole, the region has registered 869 coronavirus cases and seven deaths.
A senior Indian health ministry official in New Delhi said India had tested some 15,00 people in about 70 state-run labs, one of the lowest testing rates in the world.
Bracing for the inevitable, India is increasing the number of tests being offered.
"At this point we really don't know what is the extent of the spread," the health ministry official said, on condition of anonymity.
Officials are concerned that countries in the region will prove particularly susceptible to the virus, given poor health facilities and infrastructure in many areas.
Indian Railways, which carries more than 30 million passengers every day, said some people who had tested positive for coronavirus had travelled by train — forcing officials to track down fellow passengers.
R.D Bajpai, a spokesman for India's national railway system, urged people not to travel.
In West Bengal, inmates at the largest jail launched a violent protest against authorities for banning visitors due to the virus.
"An attempt was made by inmates to set fire to the jail after the convicts fought with the staff but the situation is under control," said an official at the Dum Dum prison, adding that police fired tear gas to quell the unrest.
In neighbouring Bangladesh, jail authorities limited the number of visitors and banned the arrival of all flights from midnight except from China, Hong Kong and Thailand, after 20 people tested positive, a senior civil aviation official said.
At Dhaka airport, authorities started marking the hands of passengers who had been instructed to follow home quarantine.
In Sri Lanka, which has reported 72 confirmed cases, police arrested 30 people from various parts of the country for violating curfew, a police spokesman said, adding that the curfew has been imposed till Monday morning.
Indians in urban centres were scrambling to buy essential commodities, ahead of a self-imposed day-long curfew on Sunday promoted by Prime Minister Narendra Modi to practice social isolation.
India, the world's second most-populous country, also plans to halt all incoming international flights to help stem the number of cases, which passed 271 on Saturday.